Genjutsu are techniques that are produced in a similar fashion as ninjutsu, in the sense that they both are types of jutsu requiring chakra and hand seals. However, the largest difference between the two is simply that the effects of genjutsu are illusory, while ninjutsu attacks are physical. Instead of attacking the victim's body, like taijutsu or ninjutsu, genjutsu techniques manipulate the flow of chakra in the victim's brain, thus causing a disruption in their senses. As a side note, or fun fact, genjutsu use requires the ability to release Yin chakra. Genjutsu is often used to create false images or to cause pain from trauma (because the body is led to believe it is in pain); however, there are plenty of other uses depending on the situation. They are not used as often as ninjutsu because they don't physically harm the opponent, however, when given to a tactful and quick witted individual, genjutsu can become a very powerful weapon. Genjutsu is produced when a ninja extends their chakra flow through the cerebral nervous system of their opponent to control their mind, thereby affecting their five senses. Those possessing special abilities like the Uchiha clan's Sharingan, or with high intelligence have an easier time executing and countering genjutsu, as attention to detail is key. Those under the influence of genjutsu can appear many ways - either appearing to be unconscious or continue to move around under the effect of the genjutsu. Because genjutsu affects activity throughout the prosencephalon structure of the brain, humans, dogs and other species of mammal are therefore all affected by genjutsu. This said, insects, such as the Auburame's kikaichū, lack such a structure to their brains, and thus do not even notice attempted illusion jutsu.

The Basic Rules:

These are the most basic and fundamental rules that are within genjutsu grading, and are to be taken into account whenever modding genjutsu. The first and most absolute rule regarding genjutsu is that they cannot layer unless the shinobi has the layering specialization. Genjutsu is something that generates a control over the senses, and that occurs at differing ranks of genjutsu. Below is a short guide to what is to be expected at each rank of genjutsu:

Academy Level | D Rank:These are the most basic genjutsu of them all. Genjutsu of this rank should be extremely minor, and hardly even applicable to a battle situation. What is more, genjutsu that function on this amount of chakra will not be able to last nearly as long as genjutsu of higher ranks. These genjutsu will only be able to manipulate one sense, and this sense is completely limited. These genjutsu are weak, minor, and normally used as nothing more aesthetic aids, even in combat.Genin | C Rank:Genin level genjutsu are also very simple genjutsu. Genjutsu of this level function on lower amounts of chakra, meaning any higher end techniques of this level are unable to function for long before fading and sputtering out. These genjutsu are only able to grip on to and manipulate a single sense, and these genjutsu are minor. Because of the small amount of chakra placed in these genjutsu, they duration is limited.Chuunin | B Rank:Genjutsu of this level start to become slightly more advanced. These genjutsu have a larger load of chakra placed in them, which makes them more able bodied. These genjutsu can accomplish a grip and hold on two senses, nothing more. At this level, genjutsu can apply more to battle, and can be extended over slightly larger ranges. While these genjutsu are only at the intermediate level, and thus cannot be something stunning, they can grasp at numerous areas and can be useful in combat.Jounin | A Rank:These genjutsu are much more advanced genjutsu that can grip at and hold at numerous senses, as well as last for long periods of time. These genjutsu can become very elaborate and manipulate the opponent in a much more absolute way. These genjutsu are elite jutsu that are very useful in combat. These genjutsu are able to capture and manipulate up to three senses. Kage/Sannin | S Rank:These are the most potent and powerful genjutsu. These are extremely realistic, and one hundred percent life like. Genjutsu of this level can last for an extremely long time time, and can hold a complex manipulation on up to three or four senses at a time. No genjutsu is able to manipulate all five senses, not even these extremely elite and powerful genjutsu.

Snaring Someone In A Genjutsu - How It Is Done:

When someone wants to go about ensnaring someone else in the illusion based world of a genjutsu, they have to be careful in how they do it. The only way to actually catch someone in the illusion that want is to use one of the opponent's five senses as a way to trap them, and cause your chakra to enter their brain where it can start to drive the opponent's senses. Seeing as the five senses include hearing, smelling, tasting, seeing, and feeling, the user has those senses, and only those senses to choose from when using the genjutsu. Because of this, the user will have to cause their chakra to penetrate the mind of the target when the opening is created - this opening is created when they take note of the specific sense you caused them to notice. Because each sense is different, and opens a slightly different area for the jutsu's penetration, each different sense has a slightly different level of hold on the target's mind; when used correctly, genjutsu brought on by some senses are stronger and more firm than when brought on by a lesser sense. Below are the different senses, how they are applied to genjutsu, and where they are in terms of creating a powerful genjutsu, or a quicker, weaker genjutsu.

Auditory Genjutsu - The Use Of Sound:Each sense is balanced in the sense that the ones that are considered easier to apply, often create the weaker and easier to break genjutsu. This is the case for genjutsu that are applied through sound. This is because a sound based genjutsu is close to guaranteed to effect the target, and because of this, it is the easiest to break from. When using a sound based genjutsu, the user will lace their chakra into the sound that they are creating, and have it enter the mind when the target notices it. Examples could be sewing chakra into your voice, and then speaking, allowing the target to hear your voice, and then be caught. With this genjutsu, the rank at which someone needs to use kai, or other methods, is equal to the rank of the used genjutsu. For example, if someone laces their voice with a genjutsu of the C rank, then it will take nothing more than a C rank kai to break free. There is an exception to this, however. Should someone use their sound based genjutsu, and cause the trigger to take place in an effective way close to the ear, the genjutsu will require a kai of a single rank higher. Examples would be if someone whispered, spoke, or yelled directly into someone's ear. For this, a C rank genjutsu would require a B rank kai to break free. Genjutsu specialists can dispel the C rank genjutsu with a D rank kai, or dispel the closer and more effective variation with a C rank kai. This is because genjutsu users are able to subtract the rank at which they have to use kai when freeing themselves, or others.

Visual Genjutsu - The Use Of Sight:This is the most used form of genjutsu, and one of the more balanced ways to use it. While it is effective in capturing the target in genjutsu, it is not guaranteed. However, this smaller chance of success allows for a slightly more gripping and firm effect of genjutsu. Visual based genjutsu can be close to anything, such as a movement of the hand, the opponent noticing the specific movement of a sword's blade, or even eye contact. For these different kinds of visual cues, there are different levels, just like the different ways to apply sound based genjutsu. For smaller bodily gestures, such as finger and wrist movements, the target can break the genjutsu with a kai of a single rank below the genjutsu's level. With larger bodily movements, such as swinging the arms, the kai rank is at the same level as the genjutsu. For eye contact, the genjutsu are generally slightly stronger. Should someone give a small look to the user's eyes, the genjutsu has to be released with an equal rank kai. With about one to four seconds of eye contact, the genjutsu can only be broken with a kai of a single rank higher. Finally, with the longer eye contact that is held over a longer period of time, anywhere from five seconds and onward, the user can cast a genjutsu that requires a kai of at least two ranks higher, in terms of chakra cost. Genjutsu specialists subtract a single needed rank of kai from the above rules, allowing them to break free a single rank easier in each of those situations.

Scent Genjutsu - The Use Of Smell:This is the art of applying a genjutsu onto someone through the sense of smell. This is done by sewing the user's chakra into a strong odor that can then be smelled by the target, and enter the mind and brain that way. These scents can take any form, and can be laced into things like smokes, rotting foods, or potent perfumes. What is more, since this is a rather uncommon form of genjutsu, the genjutsu produced are stronger than some others, but work slightly differently. This difference is that the strength of a scent based genjutsu is not always the same, and changes quickly. It is because of this that subtle scent based genjutsu are key, seeing as they will go unnoticed, and only continue to become stronger. After a scent based genjutsu is applied, it starts off weak, and grows stronger. Every post that passes without the genjutsu being noticed and broken out of, it gets stronger and stronger. For the example, we will assume that the genjutsu cast was of the B rank level. Taking that into account, this is how the genjutsu would effect the user throughout the posts, and how easy it is to kai out of at different points (genjutsu specialists subtract a single rank of kai from each of these posts, allowing the first post to break the kai at D rank, second at C rank, etc):

Tactile Genjutsu - The Use Of Touch:This is a simple and to the point way to use genjutsu. While using genjutsu that require this kind of trigger, the user must cause the opponent to feel something that has been set up with the user's chakra. This can be a vibration caused from something, or other stimulus. These genjutsu can be very useful to someone that does not mind coming close to another person in combat, and has the opportunity to use the sense of touch. Touch based genjutsu in this way dispel at the same rank of the genjutsu used. Should the user make a stronger, more powerful touch, or something placed heavily on the skin, or even rely on a softer touch that is held for longer to the target's skin, the genjutsu created will dispel at a single rank higher than the genjutsu used - this makes it very effective for shinobi that also specialize in close range fighting.

Taste Genjutsu - The Use Of Taste:This is by far the most rare, and hardest way to capture someone in a genjutsu. As such, in the balancing act, it is arguably the most powerful kind of genjutsu that can be applied, and take effect in a strong way instantly. Should the user somehow manage to get the target to consume something that they have laced with their yin chakra, the user will be put into a heavy genjutsu that requires a kai of three ranks higher - effectively making a C rank genjutsu require an S rank kai to break. However, for every hour that passes, the genjutsu starts to fade, and the genjutsu's kai rate becomes a single rank lower. This means that after a single hour, the kai for a C rank genjutsu would be A rank; and after another hour, it would be B rank. For genjutsu triggers that use taste in an airborn way, like heavy mists that can be tasted, follow the scent based genjutsu rules, as they do not count in the same way.

Breaking Free Of Genjutsu:

While applying genjutsu is nearly limitless, the ways to break free are a lot less free. Pretty much, there are two main ways to break yourself from a genjutsu. The first way is through using kai ninjutsu. The ninja needs to stop the flow of chakra in their body, and then apply an even stronger power to disrupt the flow of the caster's chakra - this is called Genjutsu kai, or kai for short. This can also be done by an unaffected ninja by applying a sudden surge of chakra into the affected person, in the case that a fellow ninja breaks you free with their own kai ninjutsu. The rules for how kai is applied are orchestrated above in the differing kinds of genjutsu. These same rules apply for the other way to break yourself free - pain.

When choosing the method of breaking loose of a genjutsu, one can either choose to spend their chakra in the way of a kai, or injure themselves. Should someone injure themselves, it causes an overload of the senses, and disrupts the genjutsu, ending it's ability to be active in the target. When a kai can be used, pain of the equivalent rank can also be used. Should a C rank kai need to be used, a C rank amount of pain can also be used. Below is a chart to show what kind of pain is equal to each rank, and how one can free themselves of genjutsu using pain - more often then not, this method is only effective against lower level genjutsu seeing as the price of injuring yourself is very hefty:

D Rank: No grievous injury required, a light cut or bruise inflicted on yourself is enough to override these genjutsu.

C rank: Tissue damage required, a deep knife wound to an appendage, a dislocated joint, a torn ligament, anything in this range will break free of a genjutsu.

B-rank: Deep cut to the abdomen, broken bones, permanent damage to susceptible areas will snap you out of this rank.

A-rank: Dismembering your body such as cutting off a limb will be enough to break you free from a genjutsu of this rank.

S-rank: Death is the only way to break free of a genjutsu of this rank using pain as the method.